This application is based upon and claims priority of Japanese Patent Applications No. 2001-081908 filed on Mar. 22, 2001 and No. 2001-102934 filed on Apr. 2, 2001, the contents being incorporated herein by reference.
1. Field of the Invention
The present invention relates to a position detector and an attitude detector.
2. Description of Related Art
In this field of the art, especially in a robot vision, game machine and pointing device, various methods of detecting a position on a screen have been proposed. The typical one of the methods detects the desired position on the basis of the image of a standard or marks on the screen taken by a camera.
Examples of the above position detector are disclosed in Japanese Patent Publication Nos. Hei 6-35607, Hei 7-121293 and Hei 11-319316.
Also, a system for adjusting a video projector has been well known, in which a video camera captures a test pattern image displayed on a screen. However, if the video projector and the video camera have different vertical scanning frequencies from each other, a flickering pattern of bright and dark bands would be caused in the image taken by the video camera. In order to solve the problem, various proposals have been made, such as in Japanese Patent Publication Nos. Hei 5-30544, Hei 8-317432 and Hei 11-184445.
For example, Japanese Patent Publication No. Hei 11-184445 discloses an imaging system in which the timing of the start and the end of photographing in a video camera is controlled by generating a shutter control signal in accordance with the vertical synchronizing signal of a display apparatus.
However, there have been problems and disadvantages still left in the related arts, especially as to the convenience, accuracy or quickness of the detection.